Propulsion systems for water borne craft



Aug. 4, 1964 MEYERHOFF PROPULSION SYSTEMS FOR WATER BORNE CRAFT 4 Sheets-Sheet 1 Filed March 8. 1961 INVENTOR. (to/W 0 Maywuorr 4, 1964 L. MEYERHOFF 3,143,097

PROPULSION SYSTEMS FOR WATER BORNE CRAFT Filed March a, 196 1 Y 4 Sheets-Sheet 2 INVENT (Ea/mp0 MU F Aug. 4, 1964 MEYERHOFF 3,143,097

PROPULSION SYSTEMS FOR WATER BORNE CRAFT Filed March 8, 1961 4 Sheets-Sheet 3 F 6 W m p p m r M A W a A118. 4, 1964 L. MEYERHOFF 3,143,097

PROPULSION SYSTEMS FOR WATER BORNE CRAFT Filed March a, 1961 4 4 Sheets-Sheet 4 TiEJE.

INV EN TOR. awvmpo five/9110f;

United States Patent 3,143,097 PRGPULSIQN SYSTEMS FOR WATER BQRNE CRAFT Leonard Meyerhoif, Brooklyn, N.Y., assignor to Eastern Research Group, a parmership Filed Mar. 8, 1951, Ser. No. 94,388 24 (Claims. (CI. 13.4-66.5)

This invention relates to water borne craft equipped with propulsion systems which are used in combination with means to produce hydrodynamic forces which maintain such craft at a position above the normal displacement position.

The trend in ship design is toward those types of craft which can operate with a minimum of wetted hull surface. Such operation is obtained by using hydroskids or hydrofoils to impart an upward force to the hull due to the flow of water on the lifting surfaces of the hydroskids or hydrofoils. These craft are termed herein as hydrodynamically lifted water borne craft.

In general, the characteristics and propensities of-hydrofoils and hydroskids are well known in the art, and the size or surface area needed to raise a given weight of ship completely out of the water at given forward speeds can be easily calculated by one skilled in the art. It is to be appreciated that the term hydrofoil is used herein to denote a member which is in contact with water on all of its surfaces. That is to say, a hydrofoil is completely submerged at all times. On the other hand, the term hydroskid is used herein to denote a member which, generally, during rying operation is in contact with water only on the underside thereof. That is to say, when the hull is lifted out of the water, the hydroskid is in contact with water only on the under surface.

One of the major problems yet to be solved in the design of water borne craft which are to operate with the hull maintained above the normal displacement position, involves providing power suflicient to drive the craft at the desired speeds. Thus, one way of propelling the craft is to house a power source in the hull of the craft and to use conventional power transmission gearing and shafts to position a propeller, for example, so that it will be submerged even when the hull is completely elevated and out of contact with the water surface. Since it is contemplated that ships and crafts of this type should be capable of speeds of 100 knots and above, the power source must be very large. As a consequence, the conventional right angle gearing and power transmission systems are not considered suitable for transmitting the power from the source within the hull to a distant point below the water surface. Such designs present formidable difficulties in high power transmission to which must be added the non-rigidity of the surrounding structures which support the right angle gear transmission. It is for such reasons that this type of design does not appear to be the solution of the problem.

Another method for providing the necessary power would be to position a power source below the water level. Since, as discussed above, the power source is necessarily very large, this second possibility would enormously increase the drag of the ship because the structure extending below the hull to house the power source would necessarily have a large cross-sectional area.

A further problem associated with known hydrofoil and hydroskid craft is that every high forward speeds are necessary before the hull can be elevated out of the water. This is due to the fact that these operate in much the same manner as an airplane in that the lifting force is proportional to the velocity squared of fluid flowing over the lifting sections.

Accordingly, it is an object of this invention to provide propulsion systems which are used in combination with 3,143,097. Patented Aug. 4, 1964 ICC meansfor hydrodynamically lifting a craft above its normal displacement position, which combination obviates the problems of power transmission'and increased drag described above.

It is another. object of this invention to provide a propulsion system for use in combination with means adapted to hydrodynamically lift a craft above its displacement position at zero forward speed.

' It is a further object of this invention to provide a craft equipped with a ducted propulsion system designed to operate in combination with a hydroskid said hydroskid being responsive to variations in the wave pattern of the water through which the craft is travelling, whereby the effect of such variations is counteracted by said propulsion system which is responsive to movement of said hydroskid.

Another object of this invention is to provide a water borne craft which operates with the hull maintained above the normal displacement position and which travels substantially on a compressed air layer which in turn is in contact with the water surface.

Briefly stated, the present invention relates to a water borne craft capable of being hydrodynamically lifted above its displacement position which comprises a hull, at least one strut attached to said hull, means attached to said strut for providing a hydrodynamic lifting force, and a propulsion system having a fully enclosed propeller, said propulsion system also having both a water inlet and a water outlet, whereby the water stream produced by the rotation of said propeller flows from said outlet thereby producing a reaction force in the opposite direction to propel said craft. In one embodiment, the propeller is housedwithin the strut, and in another embodiment the propeller is housed within a hydroskid.

Additional objects and features will become evident from the following description when taken in conjunction with the drawings, in which:

FIG. 1 is a plan view ofa hydroskid craft embodying a propulsion system of this invention.

FIG. 2 is aside elevational view partly in section. of the craft depicted inFIG. 1.

FIG. 3 is an end elevational view of the craft depicted in FIG. 1. 5

FIG. 4 is an elevational view partly in section of a modification of the hydroskid and strut employed in the craft shown in FIGS. l'through 3.

FIG 5 is a side elevational view partly in section of another embodiment'of the present invention. 5

FIG. 6 is an end elevational view of the-embodiment shown in FIG. 5.

FIG. 7 is a side elevational view partly in section of the combination of a propulsion system, hydroskid and hydrofoil in accordance with'the present invention.

FIG. 8 is an end elevationalviewof the combination shown in FIG. 7.

FIG. 9 is a modification of the combination shown in FIGS. 7 and 8.

FIG. 10 is a side elevational view partly in section of an embodiment of this invention which provides hydrodynamic lifting force at zero forward speed.

FIG. 11 is an end elevational view of the embodiment shown in FIG. 10.

FIG. 12 is a plan view of the embodiment shown in FIG; 10, I

FIG.'13 is a sectional view taken through the embodiment as shown in FIG. 10.

FIG. 14 is a side elevational view partly in section of a combination propulsion and lifting system in accordance with this invention which provides an air layer on which the craft is supported, and 7 FIG. 15 is a side elevational view of the embodiment shown in FIG. 14.

With respect now to the drawings, and more particularly to FIG. I, there is depicted a craft 1 having a hull 2. As can be seen from FIGS. 2 and 3, hull 2 is connected to a superstructure 3. Struts 4, 5 and 6 are connected to the hull 2 and superstructure 3 as shown in FIGS. 2 and 3.

Hydroskid 7 is pivotally connected to strut 5. Hydroskid 7 is pivotally connected so that the angle of inclination will follow the surface of the water and adapt to changes therein.

Hydroskids 8 and 9 are immovably connected to struts 4 and 6, respectively.

With respect to the propulsion system used for craft 1, FIG. 2 depicts hydroskid 9 and shaft 10 to which is attached propeller 11. Shaft 10 is connected directly to a power source, not shown. An opening 12 is provided in the underside of skid 9 to permit water to enter and pass through propeller 11. Cascade vanes 13 are provided in opening 12 to assist in changing the direction of flow of water from a substantially horizontal direction to a substantially vertical direction. The flow of water proceeds through opening 12, into propeller 11 and finally out of exit opening 14.

As shown in FIG. 2 there are provided flaps 15 and 16 which are pivotally connected to hydroskid 9 at points '17 and 18 respectively. These flaps serve to deflect and produced. These large lift forces may be used to lower the takeofl speed of the craft, that is to say, the craft will rise up out of the Water and be supported on the skids 7,

8 and 9 at speeds lower than if the jet were issued from opening 14 in a substantially horizontal direction.

In view of the foregoing, it is seen that the arrangement shown in FIG. 2 provides substantial lifting force at zero forward speed. This phenomenon cannot be achieved with conventional hydrofoil or hydroskid craft.

A second advantage resulting from the design shown in FIG. 2 is in the additional lift provided by the deceleration of the incoming Water stream through opening 12. By proper design of propeller 11 and passage 19, in which the water stream is ducted, an interference pattern may be developed which will cause the aforementioned deceleration. Such deceleration produces an increase in pressure in the vicinity of the underside of the rear portion of skid 9 and this increased pressure provides additional lifting force.

The power source for propeller 11 may be housed in the superstructure immediately above the skid 9. By so arranging the power transmission system extensive gearing problems are avoided and yet the power source housing does not create a water drag problem when in operation.

Hydroskid 8 is provided with propeller, passage, inlet and outlet, and flaps in the same manner as that shown for skid 9 in FIG. 2. It is to be appreciated that various combinations of propellers can be used within a single hydroskid in accordance with conventional design methods.

FIG. 4 depicts a modification of the combination hydroskid and propulsion system employed in the embodiment shown in FIGS. 1, 2 and 3. As seen in FIG. 4, strut 20 is of the same approximate shape as those shown in the previous embodiment. Likewise, hydroskid 22 is similar to that previously shown. The difference between the two embodiments is that propeller 23 is located within passage 24 in strut 21, rather than within the skid itself.

In this embodiment the water enters passage 24 through opening 25 in the underside of skid 22. Cascade vanes 26 are employed to facilitate changing the direction of the than the actual thickness ratio.

. ance with the present invention.

water stream. Flaps 27 and 28 are employed in the manner and for the purposes described in detail in copending application Serial No. 70,591, mentioned above. As is stated in the copending application, an additional set of flaps, vertically disposed, may be employed to obtain sideways defiection of the exiting water stream with resultant sideways reaction forces which may be used for steering.

The modification shown in FIG. 4 has the advantage that the propeller may be positioned closer to the power source. However, in all other respects the operation is substantially the same as the embodiment shown in FIGS. 1, 2 and 3. That is to say, the upward lift derived from the deflection of the exiting water streams by means of flaps 27 and 28 is comparable to that of the first embodiment. Also, the increase in pressure on the underside of skid 22 resulting from the deceleration of the water stream entering opening 25 is also comparable.

In the embodiment of FIG. 4, the upper end of strut 21 is necessarily widened to house propeller 23. This is advantageous from the viewpoint of rigidity and Weight. The thickened section will contribute somewhat to the drag at very low speeds, whereas at hydrodynamically lifting speeds the thickened section will be lifted out of the Water and thus the drag resistance will be eliminated.

FIG. 5 is a side elevational view, partly in section, of a third embodiment of the present invention. In this design, the propeller 29 is housed within a passage 30 contained in strut 31, similar to the embodiment shown in FIG. 4. However, as seen in FIG. 5, there is no hydroskid associated with the propulsion system of FIG. 5. As shown in FIG. 6, which is an end elevational view, hydrofoils 32 and 33 are used to provide the necessary lifting forces. The advantages stemming from location of the propeller within the strut, as shown in FIGS. 5 and 6, are the same as those for the previous two embodiments. It is to be appreciated that in the three embodiments thus far described and shown in FIGS. 1 through 6, the propeller is below the water line when the craft is in its displacement position with the hull at rest in the water. Thus there is no priming problem since the propellers are always initially covered with water.

As shown in FIGS. 5 and 6, the forward portion 34 of strut 31 is cut away to permit the water to enter. The entering water is directed upwards by cascade vanes 35. Here again, the strut is widened to house propeller 29. After passing through the propeller 29, the water stream leaves through opening 36 and then passes between adjustable flaps 37 and 38. The flaps 37 and 38 perform the same function as previously described.

Available test data show that with a strut water intake stream, such as that shown in FIGS. 5 and 6, the eifective hydrodynamic thickness ratio of the strut is less This permits the use of thicker strut sections at the lower end without appreciable change in the pressure distribution over the strut profile.

FIGS. 7 and 8 depict a fourth embodiment in accord- As shown in FIG. 7, a strut 39 is provided with hydroskid 40. In addition, a pod 41 is connected to the lower end of strut 39.

Pod 41 houses propeller 42. Water enters passage 43 within pod 41 through entrance opening 44, and leaves pod 41 through exit 45. A pair of flaps 46 and 47 is attached to pod 41, and these flaps perform the function described above.

The arrangement of FIG. 7 also includes hydrofoil sections 48 and 49. Thus, lift is achieved by a combination of hydroskid 40 and hydrofoils 48 and 49. An important advantage of the arrangement of FIGS. 7 and 8 is that hydroskid 40 may be employed to increase the weight which can be supported by such craft. Larger size conventional hydrofoil craft, for example those over 500 tons, suffer disproportionate weight increases due to the increase in structural weight of the cantilevered foils.

The elongated shape of the hydroskid is more conducive to supporting large weights similar to those of conventional ocean-going ships. Because hydroskid is designed to travel on the surface of the water it attempts tofollow the contour of such surface and the craft it is attached to may tend to have a consequent pitching motion. An advantage of the system shown in FIGS. 7 and 8 is that when rough water conditions are encountered, the flaps 46 and 47 are adjusted to provide increased lifting force suflicient to elevate skid 40 out of contact with the Water surface. In such instance, hydrofoil sections 48 and 49, in combination with lifting forces provided by flaps 46 and 47 are used to maintain the craft in a hydrodynamically lifted condition. By lifting hydroskid 40 out of the water, the uneven surface of the Water is prevented from affecting the stability of the craft as it moves through the water.

In this embodiment, hydroskid 40 also plays an important role in that it facilitates the initial lifting of the craft from the normal displacement condition to the operating condition. Hence, smaller hydrofoil wings can be used at lower speed. At higher speeds less hydrofoil lifting surface normally is needed because of the velocity square effect on lift.

FIG. 9 depicts a modification of the embodiment shown in FIG. 8. In the design shown in FIG. 9 there is provided a strut 50 and hydroskid 51 pivotable about point 52. Also provided is a pod 53 attached to the lower end of strut 50. Pod 53 is provided with propeller 54, two sets of cascade vanes55 and 56, and flaps 57 and 58. Also attached to pod 53 are hydrofoil section 59 and another hydrofoil section which is not shown in FIG. 9 but which is symmetrically positioned in the manner shown in FIG. 8.

Flaps 57 and 58 are joined together with member 59 to provide joint action. The movement of skid 51 about pivot point 52 is transmitted to flaps 57 and 58 by the combination of extensions 60 and 61 with conventional transmission means 62. Thus when hydroskid 51 moves in a counter-clockwise direction about pivot point 52, flaps 57 and 58 are inclined upwards to provide a jet stream which counteracts the movement of hydroskid 51. In other words, when the surface of the water encountered by hydroskid 51 is higher than that previously encountered,

this would ordinarily cause the craft to move upward,

since hydroskid 51 attempts to remain on the surface of the water. In order to counteract this upward movement of the craft, flaps 57 and 58 are adjusted to provide a stream of water which is deflected in in an upward direction to counteract this tendency of the carft to rise in the water. Since even the submerged hydrofoils are subjected to pitching motions of the orbital wave motion, the above arrangement will be useful for reducing undesirable pitching motion of the craft.

A further embodiment of the present invention is depicted in FIGS. 10, 11, 12 and 13. FIG. 10 is an elevational view partly in section of a strut 63 to which is connected hydroskid 64. As may be seen by a study of the end elevational view of FIG. 11 and the plan view of FIG. 12, the propulsion system depicted in the drawings has a unique water-flow pattern.

When the craft is at its displacement position, hydroskid 64 is entirely below the surface of the water. Rotation of propeller 65 causes the induction of water from the top of hydroskid 64. There is also provided passage 67 for the induction of water from below skid 64, but during the initial period this passage is sealed off by closing of valve 66. Any conventional valving system is suitable for use in this respect.

The inducted water travels through passage 68 and leaves through opening 69. A pair of flaps 70 and 87 are provided, and these flaps function in the method described above.

The arrows in FIG. 11 depict the path taken by the water as it flows into propeller 65 during submergence of skid 64. As can be seen from FIGS. 10, 11 and 13,

there is providedv an elongated dome-shaped section 71 over which the water must flow in order to reach propeller 65. The flow of water over dome-shaped section 71 causes a decrease in pressure in this region due to interelfect of known hydrodynamic forces. This decrease in pressure produces a net lifting force which thus provides lift at zero forward speed. This lift can be augmented by deflection of the issuing jet water system by appropriate manipulation of flaps 70 and 87.

As the craft rises up and approaches flying conditions, the opening of valve 66 is coordinated with the closing of valves 72 by valve actuating means 66a, valves 72 being any conventional valve assembly suitable for closing off the annular opening through which water flows to the propeller 65 from the vicinity of the upper portion of hydroskid 64. Thus, once operating conditions have been attained the operation of the propulsion system shown in FIGS. 10 through 12 is similar to that shown in FIGS. 1 through 3,

As shown in FIG. 11 hydrofoil sections may be used optionally with this embodiment to obtain additional lift.

An additional embodiment invention is depicted in FIGS. 14 and 15. This embodiment involves two features not heretofore disclosed. First, the combination propulsion system and hydroskid shown in FIGS. 14 and 15 permits the craft to travel at an elevated condition wholly supported by a layer of air positioned beneath the hydroskid. Clearly, this is advantageous since the layer of air tends to dampen any sudden vertical movements of the craft and accordingly tends to stabilize the operation. The air layer also leads to a lower fluid friction on the skid.

Depicted in FIG. 14 is strut 73 to which is connected hydroskid 74. As depicted in FIG. 14, there is an opening 75 in the forward edge of skid 74 through which water enters as a result of rotation of propeller 76. Propeller 76 is connected to a power source not shown. After the water leaves propeller 76 it is diverted into two paths, onethrough passage 78 and the other through passageway 79. The quantity of water passing through passage 79 is approximately 20% of the total and this leaves. hydroskid 74 through exit 80. The water passing through passage 78 is reversed in direction and emanates from skid 74 through exit 81. This change of direction is necessary in order to take full advantage of the reaction forces associated with the exiting jet streams for propulsion purposes.

As shown in end elevational view FIG. 15, hydroskid 74 is shaped to provide longitudinally extending sides 82 and 83. The height of these sides is chosen so that the ends thereof are well below the water surface when the craft is in flying condition. Accordingly there is developed a longitudinally-extending space 84 between the surface of the water and the underside of hydroskid '74. The streams of water emanating from exits and 81 form water curtains which seal the ends of longitudinal space 84.

A duct 85 is provided extending down through strut 73 and through hydroskid 74, terminating at opening 86 in space 84. Air is introduced through duct 85 at a pressure greater than atmospheric. The pressure used, for example, is of the order of 7 p.s.i.g. In this manner, substantially all of the weight supported by strut 73 rests on the air bubble or layer of air entrapped within space 84.

An additional advantage is derived from the curtain of water which is provided by the flow through opening 81. It is to be appreciated that the quantity of flow through opening 81 is quite considerable since this is approximately 80% of that portion of the propulsion power represented by propeller 76. During rough weather the stream of water emanating from opening 81 acts like a wedge to open a path for hydroskid 74. This wedging action, when viewed in terms of the amount of power involved, is extremely successful in permitting rough weather flying of craft of the type here described.

Although the embodiment shown in FIGS. 14 and 15 is not provided with hydrofoil sections, it is to be understood that such sections may be used to augment the lifting forces.

Several embodiments of the present invention have been described above. It is to be appreciated that in each and every embodiment described the propeller is enclosed to facilitate utilization of the jet stream of water so formed. In many of the embodiments described herein the particular inflow or outflow of the water stream resulting from rotation of the propeller is employed to create pressune differentials which provide additional lifting forces above and beyond those which stem from the use of hydroskids or hydrofoils. It is in these embodiments that the lifting force at Zero speed is greatest.

It is to be appreciated that the embodiments described above are merely intended as illustrative of the present invention, and that variations may be made thereon by one skilled in the art without departing from the spirit and scope of this invention.

I claim:

1. In a water borne craft designed to be hydrodynamically lifted above its displacement position, the combination of means for lifting the craft in response to the speed of said craft with respect to the water thereby producing hydrodynamic lifting forces, means connected to said craft for mounting said lifting means at a distance therefrom, said lifting means being located below the water line when said craft is at said displacement position, and a propulsion system extending upwardly adjacent an upwardly extending portion of said mounting means including a fully enclosed propeller disposed below the Water line when said craft is at said displacement position, said system also having a water inlet disposed adjacent said lifting means and a water outlet, whereby water is inducted into said inlet, passes through said propeller and is ejected as a stream from said outlet, said propulsion system also including control means positioned in the vicinity of said outlet and being adapted to deflect the ejected water stream in any one of a plurality of desired directions, whereby a reaction force is produced and acts on said craft.

2. A water borne craft capable of being hydrodynamically lifted above its displacement position comprising the combination of a hull, a strut connected to said hull, means for lifting the craft, said lifting means being connected to said strut at a distance from said hull and positioned below the water line when said craft is at said displacement position, said lifting means being responsive to the speed of the craft with respect to the water and thereby producing hydrodynamic lifting forces, and a propulsion system extending through said strut including a fully enclosed propeller disposed below the water line when said craft is at said displacement position, a water inlet disposed adjacent said lifting means, and a water outlet, whereby water is inducted into said inlet, passes through said propeller and is ejected as a stream from said outlet, said system also including control means positioned in the vicinity of said outlet and being adapted to deflect the ejected water stream in any one of a plurality of desired directions, whereby a reaction force is produced and acts on said craft.

3. In a water borne craft designed to be hydrodynamically lifted above its displacement position, the combination of lifting means including a hydroskid connected to said craft and responsive to the speed of said craft through the water thereby producing hydrodynamic lifting forces, said lifting means being located below the water line when said craft is at said displacement position, and a propulsion system connected to said craft including a fully enclosed propeller disposed in a passage within said hydroskid, said passage having a water inlet and a water outlet, whereby water is inducted into said inlet, passes through said propeller and is ejected as a stream from said outlet, said propulsion system also including control means positioned in the vicinity of said outlet and being adapted to deflect the ejected water stream in a desired direction, whereby a reaction force is produced and acts on said craft.

4. The combination of claim 3 in which said lifting means includes a hydrofoil.

' 5. In a water borne craft designed to be hydrodynamically lifted above its displacement position, the combination of a hydroskid connected to said craft and responsive to the speed of said craft through the water thereby producing hydrodynamic lifting forces, and a propulsion system connected to said craft including a fully enclosed propeller disposed in a passage within said hydroskid, said passage having a water inlet and a water outlet, whereby water is inducted into said inlet, passes through said propeller and is ejected as a stream from said outlet, said propulsion system also including control means positioned in the vicinity of said outlet and being adapted to deflect the ejected water stream in a desired direction,-

whereby a reaction force is produced and acts on said craft.

6. A water borne craft capable of being hydrodynamically lifted above its displacement position comprising the combination of a hull, a strut connected to said hull, means for lifting said craft, said lifting means being connected to said strut at a distance from said hull and positioned below the water line when said craft is at said displacement position, said lifting means being responsive to the speed of the craft with respect to the water and thereby producing hydrodynamic lifting forces, and a propulsion system including a fully enclosed propeller positioned in a passage within said strut, said propeller being located below the water line when said craft is at said displacement position, a water inlet disposed adjacent said lifting means, and a water outlet, whereby water is inducted into said inlet, passes through said propeller and is ejected as a stream from said outlet, said system also including control means positioned in the vicinity of said outlet and being adapted to deflect the ejected water stream in any one of a plurality of desired directions, whereby a reaction force is produced and acts on said craft.

7. The craft of hydroskid.

8. The craft of claim 6 wherein said hydrofoil.

9, A water borne craft capable of being hydrodynamically lifted above its displacement position comprising the combination of a hull, a strut connected to said hull, a hydroskid connected to said strut, a pod connected to said strut at a point below the connection of said hydroskid, a hydrofoil connected to said pod, and a propulsion system'including a fully enclosed propeller positioned in a passage within said pod, said passage having a water inlet and a water outlet, whereby water is inducted into said inlet, passes through said propeller, and is ejected as a stream from said outlet, said system also including control means positioned in the vicinity of said outlet and being adapted to deflect the ejected water stream in a desired direction, whereby a reaction force is produced and acts on said craft.

10. The'craft of claim 9 in which said hydroskid is pivotally connected to said strut, and in which a transmission means is connected to said hydroskid to reflect the angle of pitch of said hydroskid, the said control means being connected to said transmission means where by the deflection of said control means is responsive to the said angle of pitch of said hydroskid, the said reaction force tending to counter the pitching motion of said craft.

11. A water borne craft capable of being hydrodynamically lifted above its displacement position and supported on a cushion of air which is in turn in contact with the surface of the Water, comprising a hull, a hydroskid connected to said hull, said hydroskid being provided with claim 6 wherein said lifting means is a lifting means is a substantially vertical longitudinally extending sides, the lower edges of which are located below the water line when said craft is in flying position, the configuration of the sides of said hydroskid thereby providing a partially enclosed hollow space formed by the underside of said hydroskid, the surface of the water, and the said sides, a propulsion system located within said hydroskid including a fully enclosed propeller, a Water inlet and two water outlets, the said two water outlets being disposed at opposite ends of the said sides of said hydroskid and being adapted to provide respective streams of water serving as curtains to complete the enclosure of the said hollow space, a duct terminating within said hollow space, an air supply connected to said duct whereby air at a pressure greater than atmospheric is transported to and fills said hollow space, whereby substantially the entire load resting on said hydroskid is supported by the air within said hull of space.

12. The combination of claim 11 in which means are provided in the path of. the water stream being ejected from the water outlet at the forward end of said hydroskid whereby said water is. formed into a wedge prior to its contacting the surface of the body of water on which the said craft is travelling.

13. In a water borne craft designed to be hydrodynamically lifted above its displacement position, the combination of a hydroskid, said hydroskid being provided on the upper surface with a dome extending longitudinally and having a convex cross section, and a propulsion system including a fully enclosed propeller disposed in a passage within said hydroskid, said passage having a first water inlet adapted to induct water from the periphery of said dome, and a second water inlet adapted to induct water from the underside of said hydroskid, and said first and said second inlets being provided with first and second valves, respectively, said valves being 180 out of phase, means for actuating said first and second valves between the open and closed positions thereof, the first valve being initially open and the second valve being initially closed whereby water is inducted through said first inlet by A rotation of said propeller, the flow of water over said dome caused by said induction of water creating a decrease in pressure thereat whereby the craft tends to rise, said first valve then being caused to close and said second valve being caused to open thereby providing a continuous flow of water through said propeller.

14. In a water borne craft capable of being hydrodynamically lifted above its possible displacement position the combination comprising a hull, a strut connected to said hull, a hydrodynamic lifting surface for lifting said craft, said lifting surface being connected to said strut at a distance from said hull and positioned below the waterline when said craft is in said displacement position, and a propulsion system extending upwardly adjacent an upwardly extending portion of said strut including a fully enclosed propeller, said propulsion system also having a Water inlet disposed adjacent said lifting surface and a water outlet whereby water is inducted through said propulsion system and is ejected as a propelling stream, said propulsion system also including control means positioned in the vicinity of said outlet and being adapted to deflect the ejected water stream in any one of a plurality of desired directions, whereby a reaction force is produced and acts on said craft.

15. The combination of claim 14 in which said propulsion system is positioned in a passage within said strut.

16. In a water borne craft designed to be hydrodynamically lifted above its displacement position, the combination of means for producing a hydrodynamic lifting force sufficient to lift said craft in response to the speed of said craft with respect to the water, means connected to said craft and to said force producing means at a distance from said craft for transmitting thereto said lifting force sufficient to lift said craft, and a propulsion system extending upwardly adjacent an upwardly extending portion of said transmitting means including a fully enclosed propeller disposed below the water line when said craft is at said displacement position, said system also having a water inlet disposed adjacent said force, producing means and a water outlet disposed above saidinlet, whereby Water is inducted into said inlet, passes through said propeller and is ejected as a stream from said outlet.

17. In a water borne craft designed to be hydrodynamically lifted above its displacement position, the combination of means for producing a hydrodynamic lifting force sufi'icient to lift said craft in response to the speed of said craft with respect to the water, means connected to said craft and to said force producing means at a distance from said craft for transmitting theretosaid lifting force sufiicient to lift said craft, and a propulsion system extending through said transmitting means including a fully enclosed propeller disposed below the water line when said craft is at said displacement position, said system also having a water inlet disposed above said inlet and a water outlet disposed adjacent said force producing means, whereby water is inducted into said inlet, passes through said propeller and is ejected as a stream from said outlet.

18. In a Water borne craft capable of being hydro dynamically lifted above its possible displacement position the combination comprising a hull, a strut connected to said hull, a hydrodynamic lifting surface for liftingv said craft, said lifting surface being connected to said strut at a distance from said hull and positioned below the waterline when said craft is in said displacement position, and a propulsion system extending upwardly adjacent an upwardly extending portion of said strut including a fully enclosed propeller, said propulsion system also having a water inlet adjacent said lifting surface and a water outlet disposed above said inlet, whereby water is inducted through said propulsion system and is ejected as a propelling stream.

19. In a water borne craft capable of being hydrodynamically lifted above its possible displacement position, the combination comprising a hull, a strut connected to said hull, a hydroskid for lifting said craft, said hydroskid being connected to said strut at a distance from said hull and positioned below the waterline when said craft is in said displacement position, and a propulsion system extending upwardly adjacent said strut including a fully enclosed propeller, said propulsion system also having a water inlet adjacent the lower surface of said hydroskid and a water outlet, whereby water is inducted through said propulsion system and is ejected as a propelling system.

20. In a water borne craft capable of being hydrodynamically lifted above its possible displacement position, the combination comprising a hull, a strut connected to said hull, a hydrofoil for lifting said craft, said hydrofoil being connected to said strut at a distance from said hull and positioned below the waterline when said craft is in said displacement position, and a propulsion system extending upwardly adjacent said strut including a fully enclosed propeller, said propulsion system also having a water inlet adjacent said hydrofoil and a water outlet, whereby water is inducted through said propulsion system and is ejected as a propelling stream.

21. In a water borne craft capable of being hydrodynamically lifted above its possible displacement position, the combination comprising a hull, a strut connected to said hull, a hydrodynamic lifting surface for lifting said craft, said lifting surface being connected to the lower end portion of said strut at a distance from said hull and positioned below the waterline when said craft is in said displacement position, and a propulsion system extending adjacent said strut including a fully water inlet connected to said lower end portion of said strut and a water outlet, whereby water is inducted through said propulsion system and is ejected as a propelling stream.

22. In a water borne craft capable of being hydro-' dynamically lifted above its possible displacement position, the combination comprising a hull, a strut connected to said hull, a hydroskid for lifting said craft, said hydroskid being connected to said strut adjacent the lower end portion thereof and positioned below the waterline when said craft is in said displacement position, and a propulsion system extending upwardly adjacent said strut including a fully enclosed propeller, said propulsion system also having a Water inlet in the bottom portion of said hydroskid and a water outlet and disposed above said inlet, whereby Water is inducted through said propulsion system and is ejected as a propelling stream.

23. In a water borne craft capable of being hydro dynamically lifted above its possible displacement position, the combination comprising a hull, a strut connected to said hull, a hydrofoil for lifting said craft, said hydrofoil being connected to said strut adjacent the bottom end portion thereof and positioned below the Waterline when said craft is in said displacement position, and a propulsion system extending upwardly adjacent said strut including a Water inlet disposed adjacent the lower end of the leading portion of said strut facing in the direction of movement of said craft and adjacent said hydrofoil, and a water outlet and disposed above said inlet, whereby water is inducted through said propulsion system and is ejected as a propelling stream.

24. In a water borne craft capable; of being hydrodynamically lifted above its possible displacement position, the combination comprising a hull, a strut connected to said hull, the lower end portion of the leading surface of said strut facing in the'direction of movement of said craft being swept back to the bottom portion of said strut, a hydrofoil for lifting said craft, said hydrofoil being connected to said strut adjacent the bottom portion thereof and positioned below the Waterline when said craft is in said displacement position, and a propulsion system extending adjacent said strut including a Water inlet disposed Within said swept back lower end portion of said strut, and adjacent said hydrofoil, and a water outlet, whereby water is inducted through said propulsion system and is ejected as a propelling stream.

References Cited in the file of this patent UNITED STATES PATENTS 2,139,303 Greg Dec. 6, 1938 2,303,437 'Cordova Dec. 1, 1942 2,356,349 Persson Aug. 22, 1944 2,749,870 Vavra June 12, 1956 2,993,463 McKinney July 25, 1961 3,006,307 Johnson Oct. 31, 1961 3,040,525 Cockran June 26, 1962 FOREIGN PATENTS 304,476 Italy Jan. 9, 1933 932,548 France Nov. 24, 1947 902,229 Germany a Oct. 18, 1954 959,708 Germany Mar. 7, 1957 829,880 Great Britain Mar. 9, 1960 UNIT-ED STATES-PATENT OFFICE CERTIFICATE OF" CORRECTION Patent No, 3,143,097 August 4, 1964 Leonard Meyerhoff It is'her'eby certified, that error appears in the above numbered patent requiring-correction and that the said Letters Patent should read as corrected below.

Column 1, line 64, for "every" read very column 10, lines 23 and 24, for "above said inlet and a water outlet disposed adjacent said force producing means," read adjacent said force producing means and a water outlet disposed above said inlet,

Signed and sealed this 5th day of January 1965.

(SEAL) Altest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. IN A WATER BORNE CRAFT DESIGNED TO BE HYDRODYNAMICALLY LIFTED ABOVE ITS DISPLACEMENT POSITION, THE COMBINATION OF MEANS FOR LIFTING THE CRAFT IN RESPONSE TO THE SPEED OF SAID CRAFT WITH RESPECT TO THE WATER THEREBY PRODUCING HYDRODYNAMIC LIFTING FORCES, MEANS CONNECTED TO SAID CRAFT FOR MOUNTING SAID LIFTING MEANS AT A DISTANCE THEREFROM, SAID LIFTING MEANS BEING LOCATED BELOW THE WATER LINE WHEN SAID CRAFT IS AT SAID DISPLACEMENT POSITION, AND A PROPULSION SYSTEM EXTENDING UPWARDLY ADJACENT AN UPWARDLY EXTENDING PORTION OF SAID MOUNTING MEANS INCLUDING A FULLY ENCLOSED PROPELLER DISPOSED BELOW THE WATER LINE WHEN SAID CRAFT IS AT SAID DISPLACEMENT POSITION, SAID SYSTEM ALSO HAVING A WATER INLET DISPOSED ADJACENT SAID LIFTING MEANS AND A WATER OUTLET, WHEREBY WATER IS INDUCTED INTO SAID INLET, PASSES THROUGH SAID PROPELLER AND IS EJECTED AS A STREAM FROM SAID OUTLET, SAID PROPULSION SYSTEM ALSO INCLUDING CONTROL MEANS POSITIONED IN THE VICINITY OF SAID OUTLET AND BEING ADAPTED TO DEFLECT THE EJECTED WATER STREAM IN ANY ONE OF A PLURALITY OF DESIRED DIRECTIONS, WHEREBY A REACTION FORCE IS PORDUCED AND ACTS ON SAID CRAFT. 